In a Wide Code Division Multiple Access (WCDMA) system, the transmitter transmits signals over public channels such as Common PIlot Channel (CPICH) and Synchronization Channel (SCH). Because the SCH channel is not orthogonal with the High-Speed Physical Downlink Share Channel (HS-PDSCH) that bears information data, interference would occur during demodulation of the HS-PDSCH channel. As to the CPICH, although its channelized codes are orthogonal with the HS-PDSCH, it also causes interference to demodulation of the HS-PDSCH due to impact from the multi-path channel. Elimination of the interference caused by such signals at the receiver improves the demodulation performance of the HS-PDSCH, and improves the average throughput of the WCDMA system.
As shown in FIG. 1, r represents received signals of the WCDMA system, inclusive of the interference signals. Channel estimation is performed with the CPICH in the received signals to obtain a time-domain multi-path channel estimation value h. The method for eliminating interference in the prior art is: A known interference signal generator at the receiver generates an interference signal i for sending, and performs convolution for i and h to obtain the received interference signal v. The received interference signal v is subtracted from the received signal r to obtain the received signal free of interference.
In the process of developing the present invention, the inventor finds that the valid length L of the chip-level time-domain multi-path channel estimation value h is generally more than 20 taps. To eliminate the interference signal whose length is N, the multiplying operation needs to be performed for N*L times, which involves a huge calculation load.